1. Field of the Invention
The present invention relates to a method of producing material patterns which makes use of an evaporation technique and, more particularly, to a method of producing material patterns by evaporated films, applicable to the production of integrated circuits, thin film circuits, thick film circuits and hybrid integrated circuits in which the aforementioned circuits are combined.
2. Description of the Prior Art
Conventionally, the evaporation through mask technique has been used for the production of relatively simple patterns, e.g. square pattern, nearly square but rectangular pattern, circular pattern and so forth.
However, it is impossible to obtain complicated patterns such as those mentioned below by a mere application of the evaporation through mask technique. Hitherto, for obtaining these complicated patterns, it has been necessary to take a plurality of evaporations or to adopt a combination of evaporation and photoetching techniques such that at first a film of uniform thickness is formed by evaporation and then the film is processed by photoetching to form the desired pattern. These complicated patterns include the following:
(1) a rectangular pattern having a length-to-width of more than several tens (referred to as "line", hereinafter). Particularly, a pattern in which a plurality of lines of 1 mm wide or narrower run in close proximity of adjacent ones. (An example of this pattern in shown in FIG. 1a) PA1 (2) a pattern forming a closed circuit, e.g. a doughnut-like pattern as shown, for example, in FIGS. 1b and 1c. PA1 (3) a pattern substantially but not completely in the form of closed circuit, e.g. a hairpin-shaped pattern as shown in FIG. 1d.
Usually, a plate of 50 .mu.m to 1 mm thick, made of molybdenum, stainless steel or the like material is used as the mask. In case of the pattern as shown in FIG. 1a, it is possible to enhance the mechanical strength of the mask by adopting an increased thickness of the latter. It is impossible, however, to make the clearance between adjacent patterns or pattern width for a given thickness of the mask, because of the reason concerning the mask processing. Thus, in case of the above-listed complicated patterns, it becomes impossible to maintain the mask as plane, as the required pattern clearance and the pattern width becomes smaller. For this reason, in usual cases, the evaporation method has been used only in the production of relatively simple patterns.